Tseng BS, Allen DL, Sung CK, Kasper CE, Edgerton VR.
Abstr Soc Neurosci. 1991; 17: 650.
Dept. of Kinesiology and School of Nursing, University of California, L.A. 90024, USA.
Since skeletal muscle fibers have similar biochemical properties along their length, there must be some level of coordination of protein expression among the hundreds of myonuclei per fiber. In-vitro (Vandenburgh, Science 203:265-268, 1979) and in-vivo studies (Sola, Exp. Neurol. 41:76-100, 1973) suggest that mechanical activity has a major role in skeletal muscle protein regulation. To evaluate the possibility of a mechano-linkage transduction pathway, the shape of myonuclei were observed during passive and active fiber length changes. Single rat soleus muscle fiber segments (n=6) were isolated, attached to a micromanipulator and individual myonuclei and sarcomeres were observed under Hoffman modulation (500X). Micromanipulation enabled passive stretch, while a bathing solution [pCa = 4.8] was used to initiate submaximal active contractions. The myonuclei were stained with DNA specific dyes, Hematoxylin, Hoechst or Acridine Orange. One discrete myonucleus was monitored during length changes in six fibers. A correlation of 0.90 +/- 0.07 [SD] was observed between myonuclei length and sarcomere length by directly observing the same myonucleus on the same muscle fiber as sarcomere lengths were varied passively (1.33 micrometers to 4.00 micrometers) and actively (3.80 micrometers to 1.75 micrometers). These data are consistent with the hypothesis that mechanoreceptors, mechanical-biochemical links, and/or stretch-activated nuclear pores are involved in the regulation and coordination of myonuclei within a skeletal muscle cell.
Publication Types:
Keywords:
- Animals
- Muridae
- Muscle Fibers
- Muscle Proteins
- Muscle, Skeletal
- Rats
- Rats, Sprague-Dawley
- Rats, Wistar
- Sarcomeres
- NASA Discipline Musculoskeletal
- Non-NASA Center
Other ID:
UI: 102233984
From Meeting Abstracts